Notes - GNU/Linux (general)

apt-get and aptitude can't install local packages, and installation with
dpkg -i will not install any additional dependencies (requiring an additional
apt-get install -f afterwards to resolve the deps).

The gdebi tool can install a local .deb package and resolve, download and
install any dependencies (and in case you're wondering, gdebi is not a
graphical tool, that's gdebi-gtk, gdebi's gtk front-end).